How clever of you to recognize Hisano's ring! Here's another shot from an angle. Near as I can remember, the pearl was at least 30mm by 20mm, but it could have been slightly bigger. I took this in 2014 and I was trying not to be a bother as I scooped up as many photos as possible, so I tried not to ask too many questions. It was the largest South Sea drop pearl of fine quality I can remember seeing. I'm sure I'm going to see some stunning things in Hong Kong.